Spark-plug



J. J.PLATT.- SPARK PLUG. APPLICATION FILED AUG.I8, I919.

Pat entedSept. 21,1920.

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WITNESS:

JOHN JELLIFF PLATT, or nnv'on, MILFORD, comvncrrcu'r.

SPARK-PLUG.

Specification of Letters Patent.

Patented Sept. 21, 1920.

Application filed August 18, 1919. Serial No. 318.246.

T 0 all whom it may concern:

' .Be it known that 1, JOHN J. PLA'r'r, a citizen of the United States, residing at Devon, Milford, in the county of New Haven and State of Connecticut, have invented new and useful Improvements in Spark-Plugs, of which the following is a specification.

This invention comprehends the provision of a spark plug provided with electrodes having their adjacent ends hollowed or out to form cross currents of gas and air upon the explosion of each charge, thus effectively maintaining the said electrodes free from carbon or the like.

In carrying out my invention I provide the cupped extremity of each electrode with a vent opening, defining an oil passage to drain off the oil when the electrodes are set at a sharp angle, and especially when a heavy lubricant is used; the oil passing through said vents under all conditions, serving to cool the electrodes and maintain a more constant temperature.

Another object of the invention resides in the provision of a deflector for the main electrode, to prevent oil and soot from gaining access between the casing and insulating bushing of the plug, the deflector being enameled to render the same smooth and form an insulation, thus permitting the use of a relatively large deflector for this purpose.

A still further object of the invention resides in cutting a screw thread on the outside of the metallic casing or shell to cause a rapid radiation of the heat produced by combustion, the heat following the contlnuous spiral course from the base of the shell to the top thereof, where it is picked up by the screw threads of the insulated bushing of porcelain, thus maintaining the plug at the proper working temperature.

Another object of the invention resides in providing threads'on that portion of the insulated porcelain bushing which enters the shell, to accommodate an asbestos wire packing, an arrangement which prevents jamming of the packing between the shell and insulated bushing.

The nature and advantages of the invention will be better understood when the followingdetail description is read in connection'with the accompanying drawing, the invention residing in the construction, com-.

bination and arrangement of parts as claimed. In the drawing forming part of this specification like numerals of reference indicate similar parts in the several views and where- 1n:

Figure 1 is a view in elevation of the plug constructed in accordance with my invention.

Fig. 2 1s a vertical sectional view therethrough.

' Fig. 3 is a detail view of the asbestos pack-- The plug-constructed in accordance with my invention embodies the usual metallic casing or shell 10 and the insulated bushing of porcelain 11. Carried by the insulating bushing 11 is the main electrode 12 which is preferably straight, projecting an appreciable distance beyond the lower end of the shell 10, while the opposite end projects above the bushing 11 and is threaded to accommodate the usual binding nut 13. Projecting from the lower end of the shell 10 is the electrode 14, whose free end may be disposed at any desired inclination or angle with respect to the adjacent extremity of the electrode 12.

In accordance with the present invention, the adjacent extremities of the respective electrodes are hollowed as at 15, so that upon explosion of each charge of gas a cross current of gas and air is provided to effectively maintain the said ends of the electrodes clean and free from carbon or the like. In addition to this fact, each of said extremities is provided with one or more vent openings 16 defining oil passages, to permit the oil to drain from the electrodes, especially the one which is disposed at a sharp angle with rela'- tion to the other, the vent openings being especially useful in cases where heavy lubricant is used. Furthermore, the oil passing through the vent openings 16 serves to cool the adjacent extremities of the electrodes, maintaining the latter at a more constant temperature.

Arranged within the shell 10 beneath the lower end of the bushing 11, is a deflector 17 carried by the electrode 12 as shown in Fig. 2. The deflector is curved and is utilized to prevent oil, soot or the like gaining access between the shell 10 and the insulating bushing 11. The deflector is enameled to render the same smooth, with a View of preventing the soot or oil from clinging to the deflector, the enameling also forming an insulation, by reason of which fact a very large deflector may be used in this connection.

The casing or shell 10 is exteriorly threadlid ed as 18 for the purpose of causing rapid radiation of heat produced by combustion. The threads extend from end to end of the shell, except for the flange 19 which is provided with angular surfaces to accommodate a suitable tool for applying or removing the plug as will be readily understood. The top part of the shell or casing is crimped as at 20 about the bushing 11 as illustrated in Fig. 2. The porcelain bush ing 11 has, its upper or exposed portion threaded as at 21, the threads startin at a point immediately above the crimpe portion 20 and extending to the exposed end thereof. The heat produced-by combustion follows the spiral course around the threads 18 from the base of the casing or shell 10 to the crimped portion 20, where the heat is picked up by the threads 21 forming a continuation of the spiral course defined by the threads 18. This provides for a rapid radiation of heat and also maintains the plug at a more constant and proper working temperature. The lower half or portion of the insulating bushin 11 which is fitted within the casing or shel 10 is also provided with threads 22 defining grooves in which an asbestos wire packing 23 is arranged. This packing is held properly positioned upon the ushing by means of the threads 22, and consequently jarnrnin of the packing between the shell and ushing is eliminated.

' while the packing also This facilitates the association of parts, assists in the radia tion of the heat upward. I

While I have shown and described what I consider the preferred embodiment of the invention, I desire to have it understood that T do not limit myself to the exact details inasmuch as such chan es may be resorted to when desired as fin within the scope of what is claimed.

nsaegrst l V hat is claimed is:

l. A. spark plug comprising a shell, an insulating bushing partly fitted therein electrodes carried by said shell and bush-- ing respectively, and said shell and bushing belng threaded 'exteriorly, and unltedly forming a continuous spiral passage for the radiation of heat.

2. A spark plug comprising a shell, an in sulating bushing fitted therein, said shell having one end crimped about said bushing,

' electrodes carried by said shell and bushing respectively, said shell being exteriorly threaded throughout its length, and said bushing being exteriorly threaded from its point of connection with the crimped end of the shell throughout one end thereof, said threaded portions providing for a continu ous spiral passage for the purpose specified.

3. A spark plug comprising a shell, an insulating bushing fitted therein, electrodes carried by said shell and bushing respectively, said bushing having that portion fitted within the shell grooved, and an asbestos wire packing interposed between the shell and bushing and arranged within said grooves.

a. A spark plug comprising a shell, an insulating bushing fitted therein. electrodes carried by said shell and bushing respec-- tively, said bushing having that portion fitted within the shell grooved, said shell being exteriorly threaded from end to endythe exposed portion of said bushing being exteriorly threaded to provide a continuation of the spiral passage formed by the threads of the shell, and an asbestos wire packing interposed between the shell and bushing and arranged within the said grooves of the latter.

In testimony whereof I aflix my signature.

JoHN JELLIFF rnarr. 

